The invention relates to overtoggled operating mechanisms for high voltage interrupting switches used for overhead power distribution systems that provide secure closure forces adjacent the switches to prevent against accidental blade openings. The invention is particularly useful for plural switch systems such as those found in three switch phase systems used on overhead power lines.
Overhead electric power distribution lines are supported on utility poles that may be 40-50 feet high. Horizontal supports mounted to the pole often carry various distribution apparatus. Because such distribution lines commonly operate in a three-phase system with three lines mechanically connected to the horizontal support and electrically insulated from each other, there are three associated lines that ordinarily must be switched and reconnected simultaneously for maintenance or rerouting of power. This simultaneous switching process requires some form of group operated switch system.
Group operated circuit switching devices have rotatable or sliding parts that are exposed to the weather where they may become corroded, or where they may become immobilized in the winter because of ice formed on the parts. Exposed components of a switching device are not easily operated and, in addition, are often aesthetically undesirable.
Currently, many high voltage switch operating mechanisms for overhead power distribution lines rely on a handle connected to a control shaft that passes up the utility pole to a rotatable bearing on one of the three switch phases near or at the horizontal support beam. For example, see U.S. Pat. No. 5,483,030, the disclosure of which is hereby incorporated by reference. A universal control section is securely connected to the rotatable switch phase bearing so that rotation of the bearing is translated into lateral displacement of an interphase shaft along the horizontal support beam. Conductive switch blades on each switch phase connection can be rotated into or out of electrical connection with their respective phase lines. When the handle on the control shaft is rotated, the interphase shaft rotates the switch phases. Load interrupters of the type described in U.S. Pat. No. 5,457,292, which is hereby incorporated by reference, suppress the formation of damaging arcs as the switch blades are opened.
High voltage switches are typically mounted well above ground and experience a variety of externally applied forces from weather, utility pole deformation, and vibration that can tend to open the high voltage contacts over time. Thus, the handle on the control shaft must maintain the security required to prevent unintended opening of the conductive blades. It would be a desirable advance in the art to provide an improved means independent of the handle and control shaft for securing high voltage overhead power switch blades in a closed position for service, while still allowing opening of the switch blades for maintenance.
Unfortunately, the use of a control shaft that passes up through the length of the utility pole represents a source of maintenance. It would be desirable to have a switch mechanism for high voltage overhead power systems that did not require the use of a handle and control shaft running the height of the utility pole to hold the switch blades in a closed position. If a handle was used, however, the switch mechanism would provide a means atop the pole for securing the switch components in a closed position, thereby reducing the criticality of a securing system for the ground level handle.
Traditionally, group operated switch assemblies were installed and adjusted in the field to form an overhead switching system. A typical three phase installation would include a pair of parallel horizontal support beams mounted to an upright pole. The two support beams would support the three phases and conductor tension dead ending.
The field installation required installation of three individual phases and one or more interphase shafts with subsequent adjustment control arm linkages between the switch phases for proper blade opening and closing positions. These steps were often performed atop the support pole under circumstances that were less than ideal for consistent alignment. Periodic inspection was required to prevent against premature wear or damage to the switch due to loss of proper adjustment through vibration, weathering of support components, and dimensional changes in the utility pole (e.g., twisting).
It would be desirable to have a group operated switch assembly for high voltage power lines that could be a pre-assembled switch with overtoggled operation. Manufacturing under the controlled conditions of a factory could result in a high degree of reliability and operation that would resist fluctuations in component positions over an extended period of exposure to outdoor weather.
It is an object of the invention to provide a means for securing a switch assembly in a closed and/or open position.
It is also an object of the invention to provide a switch system for high voltage three phase distribution systems that provides forces to maintain the switchblades in a closed and/or open position despite ambient wind, weather, and vibration.
A further object of the invention is a high voltage overhead distribution system switching assembly that can be pre-manufactured under controlled manufacturing conditions. The manufacture would preferably rely on a modular construction of phase switches for all the benefits that normally flow from modular systems, i.e., higher quality, lower cost, enhanced reliability, better engineering design, etc.
In accordance with these and other objects of the invention that will become apparent from the description herein, the high voltage switching assembly of the invention includes a plurality of switch phases rotated between closed and open positions by pivotable, rigid connection arms operated by a rotatable overtoggle mechanism having an open position and a closed position. Either or both of the open and closed positions may be overtoggled to secure the switch blades in position.
In a particularly preferred embodiment of the invention, a group operated circuit switching apparatus according to the invention includes a plurality of switch phases that rotate about a first axis between a closed position and an open position relative to an unmoving electrical connection on a support member in a second axis, wherein each of the switch phases is secured to a rigid switch arm with a first end and a second end extending therefrom; a rigid interphase shaft connected to each of the second ends of each switch arm whereby displacement of the interphase shaft rotates each of the switch phases from the open position or the closed position; an overtoggle mechanism that may be mounted on a first support and rotated about a third axis between an open position and a closed that is more than 90xc2x0 in rotation from the open position, the overtoggle mechanism being pivotally connected to a first end of the switch arm by a reach rod; and a handle communicating with the overtoggle mechanism that rotates the overtoggle mechanism between the closed and open positions.
The switch assembly of the present invention provides a switch operated by an overtoggle mechanism that when passing the overtoggle position snaps an adjustable stop bolt against a stop member, thereby creating positive feedback that switch blades are closed or opened with maximum force while requiring minimal operating effort for service personnel when the switch is opened or closed. The design lends itself to factory construction for advantageous quality control and optimum performance. With weather resistant structural and component materials, the switching assembly may withstand extended exposure to climatic variations without significant deterioration of switching performance.
Other objects, advantages and salient features of the invention will become apparent from the following detailed description, which, taken in conjunction with the annexed drawings, discloses preferred embodiments of the invention.